Add licensing and copyright information for all files in this repository. This
either happens in the file itself as a comment header or in the file
`.reuse/dep5`.
This commit also adds a Github workflow to check pull requests and adapts
copyright.pl to the changes.
Closes#8869
Remove support for, references to and use of "cyaSSL" from the source
and docs. wolfSSL is the current name and there's no point in keeping
references to ancient history.
Assisted-by: Daniel Gustafsson
Closes#3903
